I don't know the details about the application itself. They have asked if it is possible. I think it's some sort of a custom sales application that is written in php. It's not related to WordPress at all and there are no plugins or anything for it.

What is the workaround? I just want to let them know whether it is possible or not and how easily it can be done.

So you can actually use location1.example.com/someapp/ as the defined location. If the app doesn't need to know it's real URL and can work relative, it's much easier. If it HAS to know it's real URL, I'm pretty sure it'll still work.

Now obviously that means every site would work -- location2.example.com/someapp would be a valid URL. So if that's an issue, you'd want to put in a .htaccess redirect in that someapp folder to say 'If you didn't come here from location1.example.com, redirect to ....'